Rigid thermoplastic food containers can be classified into two distinct categories. The first category of containers comprises containers that the consumer acquires during the purchase of dairy or deli foods at a retail store. A container in this category is often referred to as an “inexpensive” container, since it is usually the consumer's intention is to purchase the food in the container irrespective of the type of container. Since the consumer pays the retail price necessary to purchase the food, they often deem the container an inexpensive item that they can save for re-use at a later date.
With respect to this first category of container, a sub or first group includes the inexpensive convenience containers that consumers frequently acquire when purchasing deli foods. Generally, these “deli” containers need only to perform the function of providing a highly visible display and to provide containment of solid foods, such as, bakery items, salads or fruit, at refrigeration temperature to ambient temperature. The noted containers are often manufactured into many shapes by a thermoforming process so as to provide a wall thickness of about 10-20 mils. This wall thickness range represents the low end of wall thicknesses generally seen in rigid thermoplastic food containers and, as a consequence, the containers can be made very inexpensively. Thus, the consumer may deem the container disposable, i.e., discardable without significant monetary loss that can be attributed to the cost of acquiring the container.
“Dairy” containers, which are designed to hold butters, fresh and processed cheeses, yogurts, and read-serve sauces at retail, represent a second group of thermoplastic containers that can be characterized as “inexpensive”. Like the “deli” containers, the “dairy” containers can be made very inexpensively and, as such, the consumer may similarly deem the container disposable after limited re-use.
The noted “inexpensive” containers typically include a removable rigid thermoplastic lid that is adapted to engage the container bottom. To enhance sealing of the container, the lid is often placed over a foil or thermoplastic barrier film (i.e., lidding material).
The second category of food containers consists of expensive durable containers, which generally utilize more expensive plastic materials and thick container walls. These containers address the shortcomings of the inexpensive containers in that they may be suitable for microwave, dishwasher, and freezer use and provide a secure seal that will not leak. The noted containers also employ thicker, more durable lids.
One frustration that consumers have experienced with conventional container lids is organizing and, hence, storing of the lids. Indeed, the lids are often misplaced and difficult to find. Storing of the lids is typically addressed by incorporating stacking features to facilitate stacking or nesting of the lids.
Various lid designs have been employed to facilitate stacking. One commonly employed design comprises the provision of circular peripheral sealing ribs of somewhat U-shaped cross section that are adapted to be introduced into container openings. Stackable container lids of this kind typically include a ring-shaped, flat outwardly radially-extending peripheral flange that surrounds the sealing rib and serves as a retainer rim to be fused or sealed to the opening of the container. The stacking seating surfaces of the lids are rounded at the bottom of the sealing rib and interact with correspondingly rounded edges of an underlying identical lid at those transition points of the latter which are disposed between the inner peripheral wall of the sealing rib and the lid bottom or body, and/or at the transition points which are disposed between the outer peripheral wall of the underlying sealing rib and the associated peripheral flange or retainer rim.
A further stackable lid design includes beveled locking elements that are disposed in the snap of the container lid, the rim extending essentially downwardly and being adapted to lock over the peripheral rim of the container. The beveled locking elements are adapted to the height of the stacking ring means and with respect to the annular stacking seating surfaces of the lid such that when the elements slide over the transition rim of an identical underlying lid, the overlying stacking ring means can be readily lifted out of the circular opening or slot formed by the annular groove in the top side of the ring in the lower lid.
There are several drawbacks and disadvantages associated with prior art stackable containers. First, since the stacking means (or configuration) is disposed proximate to or an integral feature of the outer flange and/or sealing means of the lid, the stacking means only facilitates stacking of “identical” or “substantially similar” lids (i.e., same size and configuration). Second, stacking of such lids can, and in many instances will, overstress the flange and, hence, sealing means, which will have an adverse impact on the sealing integrity. Third, since the noted lids are engaged proximate the periphery, disengaging the lids is often difficult. Finally, none of the prior art lid designs address the issues of lid control and organization.
It would thus be advantageous to provide a durable container lid that is adapted to tightly seal a container, includes stacking means that facilitates stacking of a plurality container lids having similar and dissimilar sizes and configurations, and, after being engaged to another like lid, can be readily disengaged therefrom. As will be appreciated by one having ordinary skill in the art, a lid having the noted features would make organizing and storing of multiple lids easier and more convenient.